Taking a look at the history of soil pollution, some people would assign it to the start of agriculture some 11,000 years ago, while others tie it to the advent of the nuclear era starting from 1945. But still the most accurate idea of the advent of soil pollution can be thought of the time when beginning of the industrial revolution took place - primarily 1780's to 1830's. 

Soil pollution is actually caused by the presence of xenobiotic (human-made) chemicals present in the natural soil environment. The most common chemicals involved are petroleum hydrocarbons, solvents, pesticides, lead and other heavy metals which get deposited in the soil by means of industrial activity and improper disposal of waste. Contamination is correlated to the degree of industrialization and intensity of chemical substance. 

Not unexpectedly, soil contaminants can have significant deleterious consequences for ecosystems. Contaminants typically alter plant metabolism, often causing a reduction in crop yields. This has a secondary effect upon soil conservation, since the languishing crops cannot shield the Earth's soil from erosion. Also, heavy metals and other soil contaminants can adversely affect the activity and abundance of soil microorganisms, thereby threatening soil functions such as biochemical cycling of carbon and nitrogen.